Pneumatic isolator

ABSTRACT

A pneumatic spring device of the type embodying a rolling sleeve seal comprising improved means for clamping and hermetically sealing the ends of the seal to two members that are capable of displacement relative to one another. Each clamping means comprises a pair of cooperating sealing members that engage opposite sides of an end of the seal and have unique rib-groove configurations that produce a strong gripping action without damaging the seal or so distorting it as to increase its likelihood of failure under continuous and changing loads.

United States Patent Hotz, Jr. et al.

[ PNEUMATIC ISOLATOR [75] Inventors: Kenneth J. Hotz, Jr., Chatsworth;

Edward Steiner, Sun Valley; Gary L. Fox, Los Angeles, all of Calif.

[73] Assignee: Barry Wright Corporation,

Watertown, Mass.

[22] Filed: Nov. 10, 1972 [21] Appl. N0.: 305,373

[52] U.S. Cl 267/65 R, 213/43, 188/298, 74/182 [51] Int. Cl. 360g 11/26[58] Field of Search... 267/65 R, 65 B; 213/43; 188/298, 322, 314, 315;74/182 [56] References Cited UNITED STATES PATENTS 3,031,180 4/1962Sergay 267/65 R 3,046,003 7/1962 Schultz 3,157,396 11/1964 Long3,171,643 3/1965 Roos..... 3,468,433 9/1969 Peterson 3,627,297 12/1971Gaydecki Jan. 29, 1974 3,679,069 7/1972 Shaver 213/43 3,726,419 4/1973Anderson et a1. 213/43 FOREIGN PATENTS OR APPLICATIONS 1,029,290 5/1966Great Britain 267/65 B Primary ExaminerRobert G. Sheridan AssistantExaminer-R. B. Johnson Attorney, Agent, or Firm-Schiller & Pandiscio;Milton ErGilbert, Esq.

[5 7] ABSTRACT A pneumatic spring device of the type embodying a rollingsleeve seal comprising improved means for clamping and hermeticallysealing the ends of the seal to two members that are capable ofdisplacement relative to one another. Each clamping means comprises apair of cooperating sealing members that engage opposite sides of an endof the seal and have unique ribgroove configurations that produce astrong gripping action without damaging the seal or so distorting it asto increase its likelihood of failure under continuous and changingloads.

15 Claims, 4 Drawing Figures 34] *6 km in: 2 g 48/ 5O PAIENIEDM3.788.628

sum 1 or 2 N to g N m w Maw 53% mo 9? k mmv i: 1 r0 I} PNEUMATICISOLATOR This invention pertains to means for attenuating mechanicalshock and vibrations and more particularly to an improvement inpneumatic shock and vibration isolators.

A number of pneumatic spring systems useful as vibration and shockisolators are known to persons skilled in the art. Such isolators areavailable in a wide variety of sizes and load capacities and can bedesigned with special characteristics so as to provide shock andvibration protection for virtually any type of equipment or structure,e.g., machinery, electronic systems, piping and pipelines, etc. Thepresent invention is concerned with pneumatic isolators of the type thatembody rolling sleeve seals.

Rolling sleeve seal pneumatic springs offer the specific advantages ofconstant effective area, low spring rates, relatively small size sincehigh gas pressures can be used, relatively low friction, outstandingshock and vibration isolation, and variable load carrying capacity overa wide range. However, it has been determined that the useful life ofsuch devices frequently is terrninated by failure of the rolling sleeveseal, notably at one of its ends. This problem is most severe in devicesthat are intended to attenuate massive forces and large amplitudemotions as encountered in earthquakes and high impact explosions. Suchdevices typically are required to operate at pneumatic pressures inexcess of 500 psi. and to have load capacities and deflections as highas 20,000-50,000 pounds and 1 -20 inches. The stresses imposed duringthese operating conditions are a primary cause of the failures of therolling sleeve seals. In this connection it is to be noted that thefailures usually consist of detachment of one end or the other of therolling sleeve seal, but in some cases it is due to deterioration of anend of the sleeve seal.

Accordingly the primary object of this invention is to provide improvedpneumatic isolators of the type embodying rolling sleeve seals.

Another object is to provide improved means for anchoring the ends ofrolling sleeve seals.

A third object is to provide pneumatic vibration and shock isolatorsthat are capable of relatively large loading capacities and deflectionsand have relatively long useful lifetimes.

Another object is to provide isolators of the type described that havemeasured response frequencies in the range of 0.4 Hz to 1.0 Hz, withdamping in the range of 10-25 percent of critical, in the preferredembodiment.

A further object is to provide an improved pneumatic isolator that ischaracterized by controlled damping.

Still another object is to provide an improved pendulum type pneumaticisolator.

A still further object of the invention is to provide in a pneumaticisolator sealing means which substantially eliminates leakage of fluidfrom a pressurized chamber having an expansible element, so that it maybe used as a passive isolator.

Described briefly the improvement offered by the present inventioncomprises provision of novel means for clamping the ends of a rollingsleeve seal, the clamping means in each case comprising a pair ofcooperating members that engage opposite sides of a seal end and haveunique rib-groove or toothed configurations that produce a strongpositive gripping action without damaging the seal or so distorting itas to increase its likelihood of failure under continuous and changingstresses. Other features and many of the attendant advantages of theinvention are disclosed by the following description of a preferredembodiment of the invention which is to be considered together with thedrawings wherein:

FIG. 1 is a longitudinal sectional view of a pendulumtype pneumaticisolator constituting a preferred embodiment of the invention;

FIG. 2 is a cross-sectional view taken along line 2 2 of FIG. 1; and

FIGS. 3 and 4 are fragmentary views on an enlarged scale showing how therolling sleeve seal of the device of FIG. 1 is anchored according to thepresent invention.

Referring now to FIG. 1, the illustrated embodiment of the inventioncomprises a housing 2, a load cylinder assembly 4, and a damping chamberassembly 6. The housing is in the shape of a cylinder that is open atboth ends and has a circular flange 8 surrounding and welded to one end.Flange 8 is provided with a series of evenly spaced holes 10 toaccommodate bolts (not shown) for attaching the device to a suitablesupport or structure.

The load cylinder assembly 4 comprises a cylinder 12 having a circulartension rod flange 14 welded to one end as shown. Flange 14 is in theshape of an annulus and is provided with a peripheral groove in which ismounted a ring 16 made of a nylon, or other suitable low frictionmaterial. The ring 16 is so shaped (see FIG. 3) that it is retained inthe groove in flange 14 after assembly. The outer surface of ring 16presents a cylindrical surface and its diameter is such that uponassembly the ring makes a loose sliding fit with the interior surface ofthe housing 2. Tension rod flange 14 is provided with four equallyspaced tapped holes into which are screwed four tension rods 18 (seealso FIG. 2). The opposite end of load cylinder 14 is closed off by anend cap 20 and a seal flange 22. Further details of end cap 20 and sealflange 22 are presented hereafter with reference to FIG. 3.

The opposite ends of the four tension rods 18 are coupled to a pendulumrod anchor plate 26. The latter has four equally spaced holes toaccommodate the ends of rods 18 which are threaded as shown to receivenuts 28. Mounted on each of the tension rods 18 is a tube 30. The nuts28 are set so that the tubes 30 are compressed between tension rodflange 14 and anchor plate 26. As is apparent from the abovedescription, the load cylinder assembly 4, rods 18, tubes 30 and anchorplate 26 form an integral unit that is moveable along the housing 2. Inthis connection it is to be noted that anchor plate 26 has a peripheralgroove like that of tension rod flange 14 and that a suitable ring 32similar to ring 16 is disposed in that groove. Ring 32 also is shaped soas to make a loose sliding fit with the inner surface of the housing 2.

A pendulum rod 34 is attached to anchor plate 26 by a swivel jointconnection. For this purpose the plate 20 is provided with a center holein which is anchored a bearing assembly comprising a ring or race 36 anda ball 38.

Race 36 and ball 38 are connected so that the latter can rotate in amodified universal manner, i.e., it can rotate a full 360 about thelongitudinal axis of housing 2 and can also rotate :1 0 about any axisperpendicular to the longitudinal axis. The ball 38 has a diametricallyextending bore in which is secured a nut 40. One end of pendulum rod 34is screwed into nut 40. The opposite end of rod 34 is threaded toreceive a pair of nuts 42. The rod 34 is connected to the ceiling,sometimes by means of a pendant.

The damping chamber assembly 6 comrpises a cylindrical tube 44 which iswelded at one end to an end plate 46 and at the opposide end to asealing ring 48. The latter end of tube 44 is closed off by an orificeplate 50. Details of sealing ring 48 and orifice plate 50 are describedbelow with reference to FIG. 4. The end plate 46 is sized to make a snugfit with the inner surface of housing 2 and is provided with fourradially extending tapped holes to receive screws 54 (FIGS. 1 and 2)that serve to lock it to the housing. A reinforced ring 56 surrounds thehousing in line with end plate 46 and has holes aligned with the holesin end plate 46 through which extend the screws 54. End plate 46 has 4equally spaced longitudinally extending holes 58 that are aligned withthe four tension rods 18 and are oversized with respect to the tubes sothat the load chamber assembly can reciprocate longitudinally within thehousing 2.

As seen in FIG. 2, the reinforcing ring 56 is split and extendsapproximately 320 around the housing. In between the ends of ring 56 thehousing is provided with a hole 60. The latter is aligned with acounterbored radial hole 62 in end plate 46 which is threaded to receivea self closing air valve 64. By way of example, valve 64 may be a tirevalve. The bore 62 communicates with a cavity 66 in end plate 46. Cavity66 is open to the interior of tube 44 and functions as an inlet port forthe damping chamber 68.

Referring now to FIG. 3, the seal flange 22 has a peripheral groove 70whose sides are inclined as shown and disposed in the groove is a lowfriction ring 72. The ring 72 is so shaped as to be retained in the sealflange 22 and so that its outer surface makes a loose sliding fit withthe interior surface of housing 2. Although not shown in detail, it isto be noted that the rings 16 and 32 are shaped like ring 72 and thatthe grooves in which they are disposed have the same cross-sectionalconfiguration as groove 70.

A flexible rolling sleeve seal 74 is disposed between the load chamberassembly and the damping chamber assembly. Sleeve seal 74 is made of asuitable material, e.g., a textile fabric impregnated with a natural orsynthetic elastomer such as natural or silicone rubber or an elastomerreinforced with cords 75 which may be of nylon. The seal issubstantially non-stretchable under the pressures to which the device isnormally subjected, e.g., pressures up to about 800 psi. A more detaileddescription of the composition of seal 74 is not believed necessarysince such seals are well known in the art and since seals of variouscompositions may be used in practicing this invention. The ends of theseal are secured to the tubes 12 and 44 at the seal flange 22 andsealing ring 48 by an arrangement now to be described.

The inner surface of seal flange 22 is formed with a groove 76 toreceive the end of the tube 12 which is welded in place, alongitudinally slanted or frustoconical surface portion 78 which at oneend is flush with the outer surface of tube 12, a circumferential rib 80having the general shape of a saw-tooth in crosssection and spaced fromsurface portion 78 by a circumferential groove 82, and a cylindricalcoaxial surface portion 84. As seen in FIG. 3, the side of rib nearesttube 12 is inclined away from that tube (preferably at an angle of about55 to surface portion 84) while its second or opposite side is inclinedslightly in the opposite direction but is nearly at a right angle tosurface portion 84. Preferably this latter side of rib 80 extends at anangle of about 95 to surface portion 84. Further, the junction of thetwo sides of rib 80 is blunt or rounded a shown. The groove 82 issimilar to rib 80 in cross-sectional configuration, and preferably itsshorter side wall extends at an angle of about 95 to the cylindricalsurface of portion 84 and at an angle of about 60 to its opposite sidewall which is in the inclined side of rib 80. The base of groove 82 alsois rounded as shown, and preferably it has a radius of curvature likethat of the junction of the two sides of rib 80. The latter junction islocated further from the center axis of sealing flange 22 than theadjacent end of the slanted surface 78 and preferably the rib 80 islocated so that it would be tangent to a projection of tapered surface78. The latter surface preferably extends at an angle of about 5relative to cylindrical surface 84.

The end cap 20 is provided with a circular flange 86 on its inner sideand is undercut as shown to provide a flat annular surface 88 which fitsflat against the adjacent flat end surface of seal flange 22. The outercircumferential surface of flange 86 is formed with two ribs 90 and 92and a cylindrical surface portion 94. Each of the ribs 90 and 92 has across-sectional shape similar to rib 80. The longer inclined sides ofribs 90 and 92 preferably extend at an angle of about 45 relative to thecylindrical surface 94 and the opposite sides of the ribs are slanted inthe opposite direction at an angle of about 15 to the plane of surface88 which is disposed at a right angle to the center axis of end cap 20and tube 12. Thus the opposite sides of each of the grooves formedbetween ribs 90 and 92 and rib 92 and cylindrical surface 94 converge atan angle of about 60. The bases of these grooves preferably have thesame radius of curvature as the junctions of the opposite sides or ribs90 and 92. Additionally, rib 92 is further than rib 90 from the centeraxis of the end cap and the two ribs are disposed so that as viewed inFIG. 3 a line drawn tangent to their rounded ends will intersect thecylindrical surface 94 at an angle of about 5. In other words, a linedrawn tangent to the rounded ends or ribs 90 and 92 as seen in FIG. 3will be substantially parallel to the surface 78. Preferably the same istrue of a line drawn tangent to the bases of the two grooves in flange86. Flange 86 is spaced from the seal flange 22 so as to provide anannular gap in which one end of the rolling sleeve seal 74 is disposed.Preferably seal flange 22 and end cap 20 are designed so that the gapbetween the cylindrical surfaces 84 and 94 exceeds the wall thickness ofthe sleeve seal in its as-formed condition. Similarly, the gap betweenthe seal flange 22 and end cap 20 in the regions of the grooves oneither side of the rib 92 exceeds the normal or asformed thickness ofthe sleeve seal. On the other hand, the gap between (a) rib 90 andsurface 78 and (b) rib 92 and rib 80 are substantially less than theas-formed thickness of the sleeve seal. In this connection it is to benoted that rib 80 and groove 82 are located so as to be substantially indiametrical alignment with rib 92 and the groove formed between ribs 90and 92 respectively when end cap 20, seal flange 22 and sleeve seal 74are interfitted as shown and secured in place by a plurality of screws96 that extend through suitably located holes in end cap 20 and arescrewed into tapped holes 98 in sea] flange 22. The end portion of theseal 74 between flange 86 and seal flange 22 is expanded diametricallyand is also subjected to forces that (a) compress it in the regions ofthe narrow gaps between ribs 90 and 92 on the one hand and taperedsurface 78 and rib 80 on the other hand and (b) extrude it into therelatively large gaps between (1) groove 82 and the opposing groove offlange 86, (2) the second groove in flange 86 and surface 84, and (3)surface 84 and the surface 94. The overall result is that the end of thesleeve seal is securely gripped by seal flange 22 and flange 86 of endcap 20 in a manner which does not injure the seal, prevents it frompulling loose under pressures as high as 2000 psi, and assures againstleakage of fluid between the sleeve seal and end cap. The generalsawtooth cross-sectional configuration of the ribs and grooves issignificant since when the sleeve seal is subjected to tension thosesides of the ribs that are more nearly at right angles to ths axis oftube 12 act to restrain the sleeve seal against relative longitudinalmovement.

Turning now to FIG. 4, a similar gripping action is provided withrespect to the opposite end of the sleeve seal. In this case the outersurface of sealing ring 48 has a groove 100 to receive the end of tube44 which is welded in place, and also comprises a tapered orfrustoconical surface portion 102, a pair of ribs 104 and 106, and acylindrical surface portion 108. Preferably the surface portion 102extends at an angle of about 7 with respect to the center axis ofsealing ring 48 and the ribs 104 and 106 are arranged so as to betangent to a pro jection of tapered surface 102. Preferably also thediameter of the cylindrical surface section 108 is such that a linetangent to the ribs 104 and 106 will intersect it near or' at itsjunction with the flat end surface 110 of sealing ring 48. Preferably,the ribs 104 and 106 have the same cross-sectional configuration as therib 80 described previously, i.e., their shorter sides extend at anangle of about 5 relative to the end surface 110 (which is at a rightangle to the axis of the sealing ring) and at an angle of about 60relative to their longer inclined sides, while the junctions of theiropposite sides are rounded as shown. The grooves between surface 102 andrib 104 and between rib 104 and ribl06 have substantially the samecross-sectional shape as groove 82 described above. Preferably thesegrooves are formed so that a line drawn tangent to their bases will besubstantially parallel to surface 102 as seen in FlG. 4. The orificeplate 50 has a small orifice, or may have multiple orifices, in the formof a through bore 112 whose ends are flared or countersunk as shown.Alternatively such ends may be either straight or radiused. A sealingring 114 butts against the inner face of orifice plate 50 and has aninner surface which comprises a cylindrical section 116 and three ribs118, 120 and 122. Preferably the latter have cross-sectionalconfigurations like that of ribs 90 and 92, i.e., their longer sides areslanted at an angle of about 45 to the center axis of ring 114 and theiropposite sides are slanged in the opposite direction at an angle ofabout to the plane of end surface 110. Thus the opposite sides of eachof the ribs converge at an angle of about 60. Ribs 118, 120 and 122 areprogressively closer to the center axis of ring 114 and preferably arearranged so that a line tangent to them will be substantially parallelto surface 102. The two grooves formed between these ribs havesubstantially the same cross-sectional shape as the groove formedbetween ribs and 92 and preferably are formed so that a line drawntangent to their bases will also be substantially parallel to surface102. These grooves are located so as to be in substantial diametricalalignment with the two grooves between surface 102 and rib 104 andbetween ribs 104 and 106 when the orifice plate is brought tight againstsurface 110. Ribs and 122 are located so as to be in the same relationto ribs 104 and 106.

The sealing rings 48 and 1 14 are sized so that a space exists betweento receive the rolling sleeve seal 74. Further the gaps between (a) rib118 and surface 102, (b) ribs 104 and 120, and (c) ribs 106 and 122 areless than the as-formed thickness of the sleeve seal, while the gapsbetween the confronting grooves and between surfaces 108 and 116 aregreater than the as-formed thickness of the sleeve seal. Consequentlywhen the end of rolling sleeve seal 74 is sandwiched between sealingrings 48 and 114 and the orifice plate brought up tight against surface110, the sleeve seal will be gripped by said sealing rings in the samemanner as its opposite end is gripped between seal flange 22 and flange86 of end cap 20. It is to be noted that orifice plate 50 is secured tosealing ring 48 by a plurality of screws 124 which extend throughsuitable holes in the orifice plate and are screwed into tapped holes126 formed in sealing ring 48.

Since as described above the opposite ends of the rolling sleeve sealare attached to the load chamber assembly and the damping chamberassembly, it is preferred that it be tapered along its length so thatthe end attached to end cap 20 will have a diameter permitting it to lieagainst and be supported by the inner surface of tube 12 and the endattached to orifice plate 50 will have a diameter permitting it to lieagainst and be supported by the outer surface of tube 44.

The above-described preferred embodiment of the invention is used andoperates as follows: Flange 8 is secured to an equipment platform e.g.,a platfrom platform supports shock-sensitive equipment, while thependulum rod is secured to the ceiling (sometimes by means ofa pendentelement). In practice, the platform is suspended by a number of suchdevices. Additionally, the load and damping chambers 68 and 130 arepressurized with fluid to a suitable level, e.g., 100-300 psi.Pressurization of chambers 68 and 130 may be performed before or afterthe device is installed, depending upon the nature of the installation.As a consequence of the pressurization, the platform is supported by acolumn of compressed air in the load and damping chambers. lf now theinstallation is subjected to a shock force or a series of vibrationstending to displace the supported platform, a force out of phase withthe platform displacement is produced due to gas flow from one to theother of the load and damping chambers. The phase difference resultsfrom an increase or de crease of gas in the load chamber due to the gasflow. The net effect of this out-of-phase force is observed as dampingof the platform displacement. The frequency of vibration and the dampingis influenced by a number of factors, i.e., hole diameter, length andend configuration, which determine the effective cross-sectional area oforifice 112, and which controls the rate of fluid flow between the loadand damping chambers. When the displacement is such as to cause thependulum rod to move away from flange 8, the sleeve seal 74 rolls off oftube 12 on to tube 44. If the displacement is such as to cause thependulum rod to move toward flange 8, sleeve seal 74 rolls off of tube44 onto tube 12. In the former case gas is formed from load chamber 130into damping chamber 68. In the latter case gas is caused to flow fromdamping chamber 68 into load chamber 130.

Although the improved sleeve seal clamping means has been described inconnection with a pneumatic isolator, it is to be appreciated that theinvention is applicable to other forms of pneumatic springs and otherpneumatic devices employing a rolling sleeve seal.

It is to be recognized also that the sleeve is susceptible of beingpracticed other than as herein described. Thus, the number and sizes ofthe ribs on each sealing member may be varied, although it is preferredfor practical purposes that at least one of each pair of cooperatingsealing members have at least two ribs. Still other modifications willbe obvious to persons skilled in the art.

The advantages of pneumatic springs and particularly pneumatic shock andvibration isolators embodying the present invention are as stated in theforegoing statement of objects.

What is claimed is:

l. A pneumatic spring device comprising first and second assembliesdisposed in displaceable relation to each other, a flexible rollingsleeve seal having first and second ends and a predetermined wallthickness, first and second means hermetically securing said first andsecond ends to said first and second assemblies so as to form anexpandable-contractable pressure chamber therebetween, and a gaseousfluid within and pressurizing said pressure chamber, at least said firstmeans comprising a first outer sealing member having an inner surfaceand a second inner sealing member having an outer surface disposed inconcentric relation to each other and sized so as to provide an annulargap between said inner and outer surfaces, a portion of each of saidsurfaces having at least one circumferentially extending rib and atleast one circumferentially extending groove with the radial distancebetween a rib on one surface and a rib on the other surface being lessthan said wall thickness and the radial distance between a groove on onesurface and a groove on the other surface being greater than said wallthickness, said first tend of said rolling sleeve being disposed in saidannular gap with some portions thereof substantially filling the groovesin said inner and outer surfaces and other portions thereof beingcompressed by said ribs.

2. A pneumatic device according to claim 1 wherein said second meanscomprises a first outer sealing member and a second inner sealing memberas defined in claim 1 and the said second end of said rolling sleeveseal is disposed between and gripped by the first and second sealingmembers of said second means.

3. A pneumatic device according to claim 1 wherein said ribs have thegeneral configuration of a saw tooth in cross-section.

4. A pneumatic device according to claim 2 wherein said grooves alsohave the general configuration of a saw tooth in cross-section.

5. A pneumatic device according to claim 3 wherein said ribs eachcomprise first and second converging surfaces with one of saidconverging surfaces extending approximately radially of the sealingmember of which it is a part and the other of said converging surfacesextending at an oblique angle to the axis of the sealing member of whichit is a part, and further wherein said rib surfaces are disposed so thata tension force on said rolling sleeve seal will urge said sleeve sealtoward the first converging surface and away from the second convergingsurface of each rib.

6. A pneumatic actuator according to claim I wherein at least one ofsaid sealing members has at least two ribs with the distances betweensaid at least two ribs and the center axis of said one sealing memberbeing different.

7. A pneumatic device according to claim 1 wherein said first and secondassemblies are disposed in concentric telescoping relation with eachother.

8. A pneumatic device according to claim 1 wherein said second assemblycomprises a tube, means closing off said tube so as to form a secondpressure chamber, and at least one opening in said last-mentioned meansproviding fluid communication between said pressure chambers.

9. A pneumatic device according to claim 8 wherein said first assemblyalso comprises a tube, and further wherein said rolling sleeve sealextends along and is convoluted between said tubes.

10. A pneumatic device according to claim 9 wherein the tube of saidfirst assembly surrounds and is in spaced concentric relation to thetube of said second assembly.

11. A pneumatic device according to claim 1 wherein said first andsecond assemblies include means for connecting said device between twosupports that are capable of displacement relative to one another.

12. A pneumatic device according to claim 1 including an elongatehousing containing said first and second assemblies, said first assemblycomprising an end wall affixed to said housing, a first tube extendinglongitudinally of said housing and having one end affixed to said endwall, and means including said first means and a first end plate with anorifice affixed to and closing off the opposite end of said first tube,said second assembly comprising a second tube surrounding and spacedfrom said first tube, means slidably supporting said second tube withinsaid housing, and means including said second means and a second endplate affixed to and closing off one end of said second tube, saidrolling sleeve seal being convoluted and extending between said firstand second tubes, said pressure chamber being defined by said rollingsleeve seal, said first end plate and said second end plate, and saidfirst end wall, said first tube and said first end plate defining asecond pressure chamber that communicates with said first-mentionedpressure chamber via said orifice.

13. A pneumatic device according to claim 12 wherein said end wallincludes a passageway that communicates with ambient, and furtherincluding valve means connected to said passageway for admitting a fluidunder pressure to said second pressure chamber.

14. A pneumatic device according to claim 12 further including a rod forattaching one end of said device to a structure exterior of said deviceand means providing a swivel connection between said rod and said secondtube.

15. In a pneumatic spring device comprising first and second relativelydisplaceable assemblies and a rolling sleeve seal convoluted andextending between said assemblies so as to form a fluid pressure chamberbetween said assemblies, improved means for securing one of the oppositeends of said rolling sleeve seal to 1'0 relatively long side and asecond relatively short side in converging relation to each other sothat each rib has the general shape of a sawtooth in cross-section, saidlonger sides of said ribs being nearer than said shorter sides to theopposite end of said rolling sleeve seal.

2 3x3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORECTION Patent No. 37g Dated ,l ggy 22 I 1974 Inventor-(s) Kenneth J; HOtZ et al It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby ccnrn'egzted as shown below:

In claim 1, column 7, line 45, change "tend" to -end-;

Signed d-flsalea ibis 9&1 day of April 19m.

(SEAL) Attest:

EDWARD M .FLETOHER JR. I C MARSHALL DANN Attesting Officer Commissionerof Patents

1. A pneumatic spring device comprising first and second assembliesdisposed in displaceable relation to each other, a flexible rollingsleeve seal having first and second ends and a predetermined wallthickness, first and second means hermetically securing said first andsecond ends to said first and second assemblies so as to form anexpandable-contractable pressure chamber therebetween, and a gaseousfluid within and pressurizing said pressure chamber, at least said firstmeans comprising a first outer sealing member having an inner surfaceand a second inner sealing member having an outer surface disposed inconcentric relation to each other and sized so as to provide an annulargap between said inner and outer surfaces, a portion of each of saidsurfaces having at least one circumferentially extending rib and atleast one circumferentially extending groove with the radial distancebetween a rib on one surface and a rib on the other surface being lessthan said wall thickness and the radial distance between a groove on onesurface and a groove on the other surface being greater than said wallthickness, said first tend of said rolling sleeve being disposed in saidannular gap with some portions thereof substantially filling the groovesin said inner and outer surfaces and other portions thereof beingcompressed by said ribs.
 2. A pneumatic device according to claim 1wherein said second means comprises a first outer sealing member and asecond inner sealing member as defined in claim 1 and the said secondend of said rolling sleeve seal is disposed between and gripped by thefirst and second sealing members of said second means.
 3. A pneumaticdevice according to claim 1 wherein said ribs have the generalconfiguration of a saw tooth in cross-section.
 4. A pneumatic deviceaccording to claim 2 wherein said grooves also have the generalconfiguration of a saw tooth in cross-section.
 5. A pneumatic deviceaccording to claim 3 wherein said ribs each comprise first and secondconverging surfaces with one of said converging surfaces extendingapproximately radially of the sealing member of which it is a part andthe other of said converging surfaces extending at an oblique angle tothe axis of the sealing member of which it is a part, and furtherwherein said rib surfaces are disposed so that a tension force on saidrolling sleeve seal will urge said sleeve seal toward the firstconverging surface and away from the second converging surface of eachrib.
 6. A pneumatic actuator according to claim 1 wherein at least oneof said sealing members has at least two ribs with the distances betweensaid at least two ribs and the center axis of said one sealing memberbeing different.
 7. A pneumatic device according to claim 1 wherein saidfirst and second assemblies are disposed in concentric telescopingrelation with each other.
 8. A pneumatic device according to claim 1wherein said second assembly comprises a tube, means closing off saidtube so as to form a second pressure chamber, and at least one openingin said last-mentioned means providing fluid communication between saidpressure chambers.
 9. A pneumatic device according to claim 8 whereinsaid first assembly also comprises a tube, and further wherein saidrolling sleeve seal extends along and is convoluted between said tubes.10. A pneumatic device according to claim 9 wherein the tube of saidfirst assembly surrounds and is in spaced concentric relation to thetube of said second assembly.
 11. A pneumatic device according to claim1 wherein said first and second assemblies include means for connectingsaid device between two supports that are capable of displacementrelative to one another.
 12. A pneumatic device according to claim 1includinG an elongate housing containing said first and secondassemblies, said first assembly comprising an end wall affixed to saidhousing, a first tube extending longitudinally of said housing andhaving one end affixed to Said end wall, and means including said firstmeans and a first end plate with an orifice affixed to and closing offthe opposite end of said first tube, said second assembly comprising asecond tube surrounding and spaced from said first tube, means slidablysupporting said second tube within said housing, and means includingsaid second means and a second end plate affixed to and closing off oneend of said second tube, said rolling sleeve seal being convoluted andextending between said first and second tubes, said pressure chamberbeing defined by said rolling sleeve seal, said first end plate and saidsecond end plate, and said first end wall, said first tube and saidfirst end plate defining a second pressure chamber that communicateswith said first-mentioned pressure chamber via said orifice.
 13. Apneumatic device according to claim 12 wherein said end wall includes apassageway that communicates with ambient, and further including valvemeans connected to said passageway for admitting a fluid under pressureto said second pressure chamber.
 14. A pneumatic device according toclaim 12 further including a rod for attaching one end of said device toa structure exterior of said device and means providing a swivelconnection between said rod and said second tube.
 15. In a pneumaticspring device comprising first and second relatively displaceableassemblies and a rolling sleeve seal convoluted and extending betweensaid assemblies so as to form a fluid pressure chamber between saidassemblies, improved means for securing one of the opposite ends of saidrolling sleeve seal to one of said assemblies, said improved meanscomprising first and second concentric spaced sealing members engagingand gripping the inner and outer surfaces of said one end of saidrolling sleeve seal, said first and second members each having at leastone circumferentially extending rib engaging and radially compressingsaid one end of said seal, said ribs each having a first relatively longside and a second relatively short side in converging relation to eachother so that each rib has the general shape of a sawtooth incross-section, said longer sides of said ribs being nearer than saidshorter sides to the opposite end of said rolling sleeve seal.